U.S. Pat. No. 6,808,969 B2 concerns a first multiple lens array designed with positive-power lenses producing multiple bundles of converging light rays and a second multiple lens array designed with negative-power lenses producing multiple bundles of collimated light rays at a certain optimal separation between the two multiple lens arrays. As the axial separation between the two multiple lens arrays increases, the divergence of the entire beam of light increases. A black mask around the lenses reduces the effective light effect by converting the light into heat.
US20050135106A1 concerns a fresnel lens spotlight comprising an emergent light bundle having an adjustable aperture angle, a reflector, a lamp and at least one fresnel lens, wherein the at least one fresnel lens has a diffusing screen. The fresnel lens spot-light forms an adjustable aperture angle of the emergent light bundle. The fresnel lens spotlight preferably comprises an ellipsoidal reflector, a lamp and at least one fresnel lens to provide a homogeneously illuminated light field, where the fresnel lens has a diffusing screen.
To achieve a zoom effect, as described above, the reflector, the lamp or the front lens are movable. It is critical in a moving head light fixture to move heavy components because the centre of mass is moved during operation of the light assembly.
Movement of a front lens, a lamp or a reflector can lead to a change in the air flow inside the light assembly. Movement of the front lens can lead to a change of the air flow in the light assembly.